The present invention relates to a data network, and more particularly, relates to a host-fabric adapter and a method of connecting a host system to a channel-based switched fabric in such a data network.
A data network generally consists of a network of multiple independent and clustered nodes connected by point-to-point links. Each node may be an intermediate node, such as a switch/switch element, a repeater, and a router, or an end-node within the network, such as a host system and an I/O unit (e.g., data servers, storage subsystems and network devices). Message data may be transmitted from source to destination, often through intermediate nodes.
Existing interconnect transport mechanisms, such as PCI (Peripheral Component Interconnect) buses as described in the xe2x80x9cPCI Local Bus Specification, Revision 2.1xe2x80x9d set forth by the PCI Special Interest Group (SIG) on Jun. 1, 1995, may be utilized to deliver message data to and from I/O devices, namely storage subsystems and network devices. However, PCI buses utilize a shared memory-mapped bus architecture that includes one or more shared I/O buses to deliver message data to and from storage subsystems and network devices. Shared I/O buses can pose serious performance limitations due to the bus arbitration required among storage and network peripherals as well as posing reliability, flexibility and scalability issues when additional storage and network peripherals are required. As a result, existing interconnect technologies have failed to keep pace with computer evolution and the increased demands generated and burden imposed on server clusters, application processing, and enterprise computing created by the rapid growth of the Internet.
Emerging solutions to the shortcomings of existing PCI bus architecture are InfiniBand(trademark) and its predecessor, Next Generation I/O (NGIO) which have been developed by Intel Corporation to provide a standards-based I/O platform that uses a switched fabric and separate I/O channels instead of a shared memory-mapped bus architecture for reliable data transfers between end-nodes, as set forth in the xe2x80x9cNext Generation Input/Output (NGIO) Specification,xe2x80x9d NGIO Forum on Jul. 20, 1999 and the xe2x80x9cInfiniBand(trademark) Architecture Specification,xe2x80x9d the InfiniBand(trademark) Trade Association scheduled for publication in late October 2000. Using NGIO/InfiniBand(trademark), a host system may communicate with one or more remote systems using a Virtual Interface (VI) architecture in compliance with the xe2x80x9cVirtual Interface (VI) Architecture Specification, Version 1.0,xe2x80x9d as set forth by Compaq Corp., Intel Corp., and Microsoft Corp., on Dec. 16, 1997. NGIO/InfiniBand(trademark) and VI hardware and software may often be used to support data transfers between two memory regions, typically on different systems over one or more designated channels. Each host system using a VI Architecture may contain work queues (WQ) formed in pairs including inbound and outbound queues in which requests, in the form of descriptors, are posted to describe data movement operation and location of data to be moved for processing and/or transportation via a data network. Each host system may serve as a source (initiator) system which initiates a message data transfer (message send operation) or a target system of a message passing operation (message receive operation). Requests for work (data movement operations such as message send/receive operations and remote direct memory access xe2x80x9cRDMAxe2x80x9d read/write operations) may be posted to work queues associated with a given network interface card. One or more channels between communication devices at a host system or between multiple host systems connected together directly or via a data network may be created and managed so that requested operations can be performed.
Since NGIO/InfiniBand(trademark) is an emerging interconnect technology not yet in the marketplace, there is no known interface mechanism specifically implemented for NGIO/InfiniBand(trademark) applications. There is no known network interface card (NIC) for a host system to connect to a data network using a channel-based, switched fabric architecture to support data movement operations between communication devices at a host system or between host systems connected together directly or via a data network. Existing network interface cards (NICs) for host systems are not adapted for emerging NGIO/InfiniBand(trademark) interconnect technology and are, therefore, not optimized for NGIO/InfiniBand(trademark) functionality.
Accordingly, there is a need for an especially designed and performance-driven host-fabric adapter installed at a host system in a data network using a channel-based, switched fabric architecture, and optimized for NGIO/InfiniBand(trademark) functionality with minimal hardware investment, including controlling execution of NGIO/InfiniBand(trademark) protocols with minimal pipelining and NGIO/InfiniBand(trademark) cell data processing with minimal latency.